1. Field of the Invention
The present invention relates to an initial driving circuit of a backlight unit which is applicable to LCD monitors, TVs, and the like, and more particularly, to an initial driving circuit of a backlight unit which is capable of protecting the backlight unit by reducing an initial high-frequency driving time with the use of a feedback signal and a soft start signal.
2. Description of the Related Art
In general, a backlight inverter is used for liquid crystal display (LCD) TVs or LCD monitors employing a cold cathode fluorescent lamp (CCFL), and includes various protection circuits so as to protect internal devices.
Greater precision in the design of protection circuits is required in order to improve the quality of TVs and monitors. In order to initially drive a CCFL (hereinafter, referred to as a lamp), a protection circuit intensively lights up the lamp at a frequency higher than a normal frequency. Then, when the lamp is stabilized after the lapse of a predetermined time, the protection circuit reduces the frequency to the normal frequency.
Also, the protection circuit serves a role in protecting a transformer and an opened part of the lamp by causing the lamp to operate at a frequency higher than the normal frequency, even during abnormal operation of the lamp.
A related art backlight inverter should be driven at relatively high frequency during the initial driving operation, and should be driven at relatively low frequency during normal operation. However, an initial high-frequency driving time is determined on the basis of a voltage charged in a capacitor, and it is thus difficult to accurately determine the initial high-frequency driving time.
If a high-frequency driving time exceeds the initial driving time of the lamp, it is problematic, in that the lamp may be damaged due to an intensive driving signal.